Deflection device for cathode-ray tubes



March 23, 1937. w TOLSON 2,074,764

DEFLECTION DEVICE FOR CATHODE RAY TUBES Filed Dec. 15, 1954 Homzozvrm. VEET/CHL DEFLECT/ON DE FLE C T/ON OlBCU/T ol/acu/r 56 ""HIIIIIFIIEEF 40 I/w/E/vwg:

mamiawo JETTOENEK Patented Mar 23, 1937 UNITED STATE FOR CATHODE-RAYI E TUBS William A. Tols'on, Westmont, N. 1., assignor, by mesne assignments, to Radio Corporation of America, New York, N. Y., a corporation of Delaware Application December 15, 1934, Serial No. 757,624 2 Claims. (Cl. 250-275) My invention relates to improvements in deflection devices for cathode-ray tubes.

Cathode ray tubes of the type used for television reception comprise a fluorescent screen at one .end of the tube and means at its other end for deflecting a ray of electrons and directing the ray at the screen. The electron ray is deflected simultaneously in both vertical and horizontal directions. For this purpose, it has been found to be advantageous to use two pairs of deflecting coils mounted on a common yoke of permeable material and provided with pole pieces on which the coils are disposed.

Deflection devices of the general character referred to have been found to be effective, but the deflecting efliciency thereof has been found to be relatively low. This has been attributed to the fact that the coupling between corresponding deflecting coils is only of the order of three percent, by the fact that the vertical pole pieces unavoidably act as a leakage path for the horizontal deflecting flux, and by the fact that the horizontal pole pieces, in like manner, act as a leakage path for the vertical deflecting flux.

With the foregoing in mind. it is one of the objects of my invention to provide an improved deflection device for cathode ray tubes in which electromagnetic coils are employed for both vertical and horizontal deflection of the ray, and which has a deflecting efficiency substantially higher than that of the various constructions proposed heretofore.

Other objects and advantages will hereinafter appear.

In accordance with my invention, the deflecting coils are disposed on a common yoke provided with two pairs of pole pieces. The coils for horizontal deflection of the ray are disposed between the center of the yoke and the coils for vertical deflection of the ray, and each of the coils is disposed about two of the pole pieces which are adjacent to each other in the direction circumferentially about the center of the yoke.

My invention resides in the improved construction of the character hereinafter described and claimed.

For the purpose of illustrating my invention, an embodiment thereof is shown in the drawing, wherein Figure 1 is a side elevational view of a cathode ray tube for television reception, embodying my improved deflecting device;

Fig. 2 is an enlarged sectional view, the section being taken on the line 2-2 in Fig. 1;

Fig. 3 is a sectional view, the section being taken cent screen 12 and with means in the form of a gun M for developing a ray 16 of electrons and directing the same at the screen. The electron gun is disposed in the neck iii of the cathode ray tube upon which my improved deflection device, designated generally by the reference numeral 20, is mounted.

The yoke of my improved deflection device is comprised of a plurality of similar laminations 22 of permeable material. The outer edge 24 of each lamination is disposed on a half circle, and is provided with two pole portions 26 and 28. The respective side edges 30 and 32 of the pole pieces 26 and 28 lie respectively on the radii 30a and 32a from'the center 38 of the circle. The respective adjacent edges 34 and 36 of the pole pieces are parallel to each other and are substantially shorter than the outer edges 30 and 32.

The respective center lines 26a and 28a of the pole portions are spaced angularly from each other as represented.

Each lamination is provided with a circumferential extension 40 from the base of the pole'portion 28. The end or outer edge 42 of the extension 4!] lies substantially on the diameter of the half circle, as shown.

Each lamination is provided with holes 43 which receive bolts or rivets for holding the parts toversed With respect to each other and placed together in complementary relation as shown to.

complete the circle. In making the succeeding laminations of the yoke, the complementary pairs of laminations 22 are placed in position so that the extensions 40 at either the bottom or top, as viewed in Fig. 5, extend to the right and left alternately. When the stack is complete, therefore, the extensions 40 are interleaved, and the holes 43 are aligned to receive rivets or bolts 44 which hold the parts together.

- The electron ray I6 is deflected horizontally by a pair of coils 86 and 48. The coils 4B and '48 wave at a relatively high frequency and causes this wave to pass through the coils 45 and 418 which may be connected in series, as indicated. A circuit 53 generates a saw-tooth current wave at av relatively low frequency and causes this wave to pass through the coils 5d and 52 which may be connected in series, as indicated. In this way,

'' the ray i8 is caused to scan the-screen it over a rectangular area.

In Fig. 4 my improved deflection unit 26 is shown enclosed in a casing 59 having a central cylindrical wall 59 for receiving the neck id of the tube it. The casing 58 may be made of cardboard, and the spaces between the walls thereof and the deflection unit are filled with a suitable insulating and. waterproof material. In this way, the deflection deviceis completely encased and protected.

Deflection devices made in accordance with my invention have been found to be approximately 2.25 times as effective for deflection of the electron ray, under similar operating conditions, as the various devices constructed heretofore and employing coils for both vertical and horlzonta deflection.

While my improved deflectiondevice has been described more in association with cathode ray tubes for television reception, it will be understood that it is adaptable for use with any cathode ray tube for deflecting the ray in two directions with coils.

2,074,764 I f v While but one embodiment oi my invention has been disclosed, it will be understood that various 4 modifications within the conception. or those skilled in the art are possible without departing from the spirit of my invention or the scope or the claims.

I claim as my invention:

l. A cathode ray defiection'device comprising a yoke of magnetic material provided with two pairs of pole pieces, said pole pieces being disposed about and extending inwardly toward the center ofsaid yoke, the pole pieces of each pair being disposed respectively on diametrically opposite sides of said center, and two pairs of raydefiecting coils, the coils of one pair being disposed between said center and the coils of the other pair, each of said coils being disposed about two of the pole pieces which are adjacent to each other in the direction circumferentially about said center, each of said coils in. one pair also being disposed about two adjacent pole pieces each of which has disposed thereabout a difierent coil of the other pair.

I 2. A cathode ray deflection device comprising a substantially ring -sha'pe yoke of magnetic material having a plurality of slot-like openings disposed about the center of said yoke and extending at substantially right angles to the plane of saidring, ,a pair of deflecting coils, one of said deflecting" coils disposed in at least two of said slots, the other of said deflecting coils disposed in at least two of said,slots and positioned diametrically opposite said first coil, a second pair of deflecting coils sopositioned inside said first pair that at the center of the yoke the magnetic field produced by one pair of coils is substantially at right angles to the magnetic field produced by the other pair of coils, one coil of said second pair being disposed in at least two other or said slots in overlapping relation with said first pair of coils, and the other coil of said second pair tioned coil in overlapping relation with said first I being disposed in at least two of said slots and positioned diametrically opposite said last menpair of coils.

- A. TOLSON. 

